Lubricating compositions for compression refrigerators



United States 3,449,459 LUBRICATING COMPOSITIONS FOR COMPRESSIONREFRIGERATORS Michel Asfazadourian, Robert Muths, and Marcel Prillieux,Mont-Saint-Aignan, France, assignors to Esso Research and EngineeringCompany, a corporation of Delaware No Drawing. Filed Nov. 2, 1966, Ser.No. 591,407 Int. Cl. C07c /02; C09k 3/02 US. Cl. 260-671 7 ClaimsABSTRACT OF THE DISCLOSURE The present invention is concerned withsynthetic lubricants intended for the lubrication of compressionrefrigeration apparatus. These lubricating compositions arecharacterised by their miscibility with halogenated refrigerating fluidssuch as the fluorochlorinated hydrocarbons of the Freon type.

Synthetic oils obtained by the fractional distillation of the alkylationproducts of benzene by olefins, in the presence of a Friedel and Craftscatalyst are known; these oils are in fact miscible with refrigeratingliquids of the Freon type down to very low temperatures.

The applicants have discovered that alkylated aromatic hydrocarbons,when subjected to superalkylation, furnish products that can be used aslubricating oils for compression refrigerating apparatus.

The alkylaromatic hydrocarbons intended to be superalkylated accordingto the invention are those having from 1 to 5, and preferably 2 to 3straight or branched aliphatic chains. Each chain preferably has from 1to 15 carbon atoms.

Suitable examples are methylethylbenzene, dimethylethylbenzene,trimethylbenzene, tetramethylbenzene, or mixtures of these substances,preferably:

The product known in the trade by the name of Solvesso 100, i.e. amixture containing 92% methylethylbenzene and tetramethylbenzene andhaving as its characteristics:

Density 0.872 ASTM distillation:

Initial point C 158 50% distilled C 163 Final point C 171 Mean molecularweight 120 The product known in the trade as Solvesso 150, a mixturecontaining 70% dimethylethylbenzene and tetramethylbenzene and havingthe following characteristics:

Density 0.892 ASTM distillation:

. Initial point C 187 50% distilled C 193 Final point C 212 Meanmolecular Weight a- 135 The petroleum fraction distilling between 170 C.and 325 C., 50% distilled at 181 C., with a mean molecular weight of 136and a density of 0.905.

atent O "ice According to the invention this superalkylation takes placein the presence of a classic alkyla-tion catalyst with olefin polymers,for example a trimer, tetramer or pentamer of propylene and forpreference those complying with the following characteristics:

Propylene trimer:

Density 0.740 ASTM distillation:

Initial point C Final point C Mean molecular weight 127 Propylenetetramer:

Density 0.777 ASTM distillation:

Initial point C 183 50% distilled C..- 188 Final point C 222 Meanmolecular weight 172 Propylene pentamer:

Density 0.802 ASTM distillation:

Initial point C 269 50% distilled C 271 Final point C 303 Mean molecularweight 245 Suitable alkylation catalysts are sulphuric acid or acids ofthe Lewis type such as AlCl or BF Alkylation is performed at atemperature of 0 to 60 C. and preferably at about 40 C. the weight ratioaromatic hydrocarbon/ olefin polymer being between 7/1 and 1/ 1, andpreferably between 3/1 and 5/ 1. The catalyst represents 3 to 10% andpreferably 5 to 6% by weight of olefin. The operation takes about onehour.

The lubricating oils according to the invention make it possible toprepare mixtures with halogenated refrigerating fluids, such as thefluorochlorinated hydrocarbons of the Freon type, the proportion oflubricant being preferably 1 to 10% by Weight of the mixture.

The following example illustrates the invention.

EXAMPLE Solvesso 100 and Solvesso were superalkylated with propylenetetriamer, these substances having the properties mentioned previously.This superalkylation was performed under the following conditions:

Temperature-40 C.

Weight ratio Solvesso/tetrapropylene-5/ 1. Catalyst AlCl 6% by weight oftetrapropylene. Time-1 hour.

The superalkylated Solvesso 100 had the following characteristicsDensity 0.884 Distillation C 305/350 and the superalkylated Solvesso150:

Density 0.935 Distillation C 330 Two mixtures M1 and M2 were prepared.Mixture M1 comprised: 35% by volume of superalkylated Solvesso 100; and65% by volume of superalkylated Solvesso 150. Mixture M2 comprised: 40%by volume superalkylated Solvesso 100; and 60% by volume superalkylatedSolvesso 150.

The characteristics of mixtures M1 and M2 were determined according tothe following methods:

Flash point, open vessel NFT 60103 Density NFT 60-101 Cloud point ASTM D9757 Aniline point ASTM D 611-63T Viscosity NFT 60-100 The followingresults were obtained:

Density, 15 C 0. 906 0. 896 Flash point open vessel 168 160 Viscosity incentistokes at 37.8 0. (100 F.) 40. 21. 9 ASTM colour 3- Flocculationpoint C. 60 37 Cloud point, C -33 36 Aniline point, C 35 32. 5

1 This temperature is that at which precipitation by flocculation takesplace in a mixture of lubricating oil and 90% refrigerating fluid. It isascertained under the following conditions: 1 cc. of the oil to betested is placed in a thick glass tube; it is then heated to 120 C. anddry nitrogen is injected through the sample for about 10 minutes. Thetube is then allowed to cool to the ambient temperature and is placed ina cooling bath, whose temperature is higher by about 8.5 C. than theassumed flocculation point. There are then added 9 cc. Freon 12 (OClQFZ)and the tube is closed, After checking the homogeneity of the mixture,the tube is put back in the cooling bath and the temperature is loweredby 2.8 C. in 4 minutes and the appearance of the mixture is examinedafter 15 minutes at this temperature. The process is continued as longas is necessary by lowering the temperature of the bath by fractions of28 C. until the presence is noted of a definite precipitate in thesample. The corresponding temperature of the bath is that of theflocculation point.

It thus appears that the viscosity and the flocculation point can beascertained by varying the relative proportions of the differentsuperalkylated Solvessos used. The mixture M1 furnishes a particularlyinteresting flocculation point.

It is obvious that the present invention has been described purely byway of explanation and in no sense restrictively and that anymodifications may be made to it without departing from its scope.

We claim:

1. A process for preparing a hydrocarbon lubricating oil that ismiscible with a fluorochlorinated hydrocarbon refrigerant at lowtemperatures which comprises alkylating a mixture of aromatichydrocarbons consisting predominantly of at least two diiferenthydrocarbons from the group consisting of methyl ethyl benzene, dimethylethyl benzene, trimethyl benzene, and tetrainethyl benzene, with apolymer of propylene having 9 to 15 carbon atoms, in the presence of analkylation catalyst, the weight ratio of the said mixture of aromatichydrocarbons to propylene polymer being in the range of from 1:1 to 7:1.

2. A process as defined by claim 1 in which the alkyl aromatichydrocarbon mixture is a petroleum fraction distilling between and 325C., 50% distilling at 180 C., and of mean molecular weight 136 anddensity 0.905.

3. A process as defined by claim 1 wherein the catalyst is selected fromthe group: sulphuric acid and a Lewis acid.

4. A process as defined by claim 1 wherein said weight ratio is withinthe range of 3:1 to 5:1.

5. A process as defined by claim 1 wherein said mixture of aromatichydrocarbons is a mixture of methyl ethyl benzene and tetrarnethylbenzene.

' 6. A process as defined by claim 1 wherein said mixture of aromatichydrocarbons is a mixture of dimethyl ethyl benzene and tetramethylbenzene.

7. An improved refrigerant-lubricant composition for use in acompression refrigeration apparatus which comprises a major proportionof a fiuorochlorinated hydrocarbon refrigerant and from 1 to 10 weightpercent of the hydrocarbon lubricating oil prepared by the process ofclaim 1.

References Cited UNITED STATES PATENTS 3,092,981 6/1963 Begeman et a1252-68 3,169,928 2/1965 Herold 252-68 3,214,462 10/1965 Swenson et a1.260-671 FOREIGN PATENTS 664,095 1/ 1952 Great Britain. 665,058 1/1952Great Britain. 666,209 2/1952 Great Britain.

DELBERT E. GANTZ, Primary Examiner. C. R. DAVIS, Assistant Examiner.

U.S. C1. X.R. 252-68

